1. Technical Field
This invention relates to a method of soil improvement and dust control utilizing synthetic fluids and other non-synthetic base oils and various combinations of polyisobutylene, carboxylic acids, pour point depressants, esters, soil/ash, biodegradable fibers, wood chips, and/or synthetic fibers.
2. Background
Many methods of chemical dust and erosion control, and soil stabilization have been utilized over the years, with various detrimental effects on environment, health, and safety and varying degrees of success. Traditional products used for dust control and soil stabilization consist of used or recycled oil, virgin oils, chlorides, lignins, and emulsifications made with low-grade petroleum resins, asphalt, oil, and pitch.
The use of used or recycled petroleum oils has long been employed as a dust control agent. In recent years legislation by most states has curtailed the use of these oils for dust control because of concerns with environment, health, and safety. This legislation has spawned an interest in virgin oils, some highly refined and very safe. The highly refined products may contain low or no aromatics but are generally cost prohibitive for most applications. In addition, petroleum oils have limited value as dust suppressants and virtually no value as soil stabilizers. They act as particle weighting agents by the processes of adsorption or absorption and do not have any significant cohesive action for soil stabilization and control of fine dust.
Magnesium chloride, calcium chloride, and sodium chloride used in solution or solid form act as humectants when added to soil. These products work well in areas of sufficient moisture or require watering for humectants action. The problems with these products are their solubility in water and effects on ground water and plant life. In addition, as strong electrolytes they are highly corrosive to metal equipment.
Lignins have been employed as a low-cost means of dust control for several decades. Recently lignins have come under considerable attack by environmental, health, and safety organizations that have identified dioxin and dioxin forming compositions in lignin This problem is compounded by lignins solubility in water and its ability to contaminate ground water. Lignins also have a limited working life because they are water soluble they tend to be washed away with rain, melting snow, or other moisture.
Many types of emulsions of tall oil, petroleum resins, and asphalts and combinations can be prepared and have been exhibited in prior art. Typically these products are emulsified to reduce viscosity to sprayable levels and to aid in penetration of the product into the soil. One of the problems created is the use of excess liquid, which is sprayed onto the ground and can migrate into ground water. In addition, emulsions can also be severely damaged by rain and moisture when the moisture event occurs prior to the emulsion breaking and the active ingredients curing. When cured properly these products produce a bound soil layer, which is effective for dust control for short periods and under conditions where there is little mechanical disturbance. Examples of tall oil pitch emulsions that produce these results can be found in prior art. Doyle U.S. Pat. No. 5,895,347 discloses chemically stabilized emulsions of tall oil pitch, hydrochloric and stearic acids, and emulsifiers in water where temperature and pH are controlled during preparation. Additionally, Burch U.S. Pat. No. 4,822,425 discloses an emulsion comprising tall oil pitch, rosin, emulsifier, and water.
Different soil types are classified under the Unified Soil Classification System (USCS) with a two letter code. The first letter choices are G—gravel, S—sand, M—silt, C—clay, O—organic, and the second letter choices are P—poorly graded, W—well graded, H—high plasticity, L—low plasticity. The group symbols are GW, GP, GM, GC, SW, SP, SM, SC, ML, CL, OL, MH, CH, and OH.
Binders are defined as additives to the material being agglomerated that produce bonding strength in the final product. A binder can be a liquid or solid that forms a bridge, film, or matrix filler or that causes a chemical reaction. Binders can be classified into four types. The first type is a matrix binder which is a solid or semi-solid, such as tar, pitch, asphalt, wax, or cement. Another type is a film binder, which includes water, solutions, dispersions, powders, silicate, gel, oil, alcohol, clay, and starch. The third type is a chemical binder, which reacts chemically with the material being agglomerated; these include silicate, acid molasses, lime, and lignosulphonate. The fourth type is a lubricant, which is used to reduce friction and induce flow of the material. Lubricants include oil, glycerin, stearate, and wax.